1. Field of the Invention
The invention relates to an electronic device and a hinge assembly thereof; in particular, the invention relates to a hinge assembly that can make the operation of an electronic device more convenient.
2. Description of the Related Art
Conventional hand-held, clamshell type electronic devices are opened and closed by hinge torsion. A clamshell type mobile phone, for instance, comprises a housing with upper and lower portions joined by a hinge. The mobile phone may be manually opened to a predetermined angle, such as 30 degrees, relative to its closed state, by torsion acting on the hinge. The mobile phone may then be further opened automatically to a maximum open angle of 180 degrees relative to its closed state. Conversely, when the upper housing portion is manually returned to a 30-degree angle relative to its closed state, the upper housing is automatically closed to its closed state by torsion acting on the hinge.
The hinge is provided with a plurality of cams to obtain the above function and determine the feature of such a clamshell type device to be opened automatically at a certain angle. The device is automatically opened or closed when the angle of the upper housing portion on the hinge exceeds a critical torsion point. For example, when the cams are designed to manually open the device to a 30 degree angle; the upper housing portion of the device must then be automatically opened to the full open angle of 180 degrees. The device may also be automatically opened to the full open angle of 180 degrees after being manually opened to the initial 30 degree angle. To completely close the device from the full open angle of 180 degrees, however, the upper housing portion must be manually closed to an angle on the hinge of less than 30 degrees to automatically return the device to its original closed state. The manual action required to return the upper housing of the electronic device to the original closed state from the full open angle of 180 degrees could possibly be considered inconvenient, hence, a hinge assembly that simplifies the opening and closing action is called for.